Methods of polyvalent bacteriophage preparation for the treatment of bacterial infections

ABSTRACT

The multivalent strains of bacteriophages, methods of obtaining these and their use in the treatment of bacterial infections, particularly those of drug-resistant bacterial strains, especially arising in mucoviscidosis patients, are provided.

FIELD OF THE INVENTION

The present invention concerns multivalent strains of bacteriophages, methods of obtaining these, and their application in the treatment of bacterial infections, particularly those of drug-resistant strains of bacteria.

BACKGROUND OF THE INVENTION

The bacteriophages (phages) are a diverse group of viruses whose life cycle is connected exclusively with bacteria cells. Bacteriophages are characterized by a lysogenic or lytic life cycle. As anti-bacterial agents, lytic bacteriophages are especially useful which, after infection by bacteria cells to which they are sensitive, they replicate within them, leading to their total destruction (by lysis) and the release of new phages which attack and destroy subsequent bacteria cells. This process may occur both in vitro and in vivo.

One of the essential characteristics of bacteriophages is the well-known high specificity of their lytic activity. This feature is exploited in, for example, species determination (phage typing) of various bacteria (see, for example, patent descriptions GB 2285684, U.S. Pat. No. 5,824,468 and SU 543260, as well as the international patent notifications WO 0100786 and WO 0109370). Other known applications of bacteriophages include their usefulness as tools in molecular biology, for example in the expression and selection of specific proteins (e.g. patent description U.S. Pat. No. 6,027,930), and in sterilization and cleansing media (e.g. patent descriptions EP 0414304, EP 0290295 and GB 2253859, as well as the international patent notifications WO 9808944 and WO 9003122). Modified phages are used in the production of vaccines (e.g. WO 9505454). Certain proteins of bacteriophage origin are also used (e.g. EP 0510907, U.S. Pat. No. 5,470,573, WO 9607329). The methods of isolating bacteriophages and obtaining phage preparations are well known and are constantly being perfected (e.g. GB 829266, CS 192212, RU 2109055).

Phage therapy has been employed on a wide scale since the Second World War at the Institute of Microbiology and Virology of Tbilisi, Georgia. A bank of various phage preparations is used there in the treatment of bacterial infections and in prophylaxis.

Available data indicate a great effectiveness of phage therapy. Similar research has been conducted in Poland for over 25 years. At the Bacteriophage Laboratory of the Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences in Wroclaw the phage therapy is used treatment of infections caused by drug-resistant forms of bacteria and those not susceptible to antibiotics (see: Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1981, 31, 293; Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1983, 31, 267; Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1984, 32, 317; Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1985, 33, 219; Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1985, 33, 241; Stefan Ślopek et al., Archivum Immunologiae et Therapiae Experimentalis, 1987, 35, 569; Beata Weber-Dabrowska et al., Archivum Immunologiae et Therapiae Experimentalis, 2000, 48, 31-37; Beata Weber-Dabrowska et al., Archivum Immunologiae et Therapiae Experimentalis, 2000, 48, 547-551). The phage therapy carried out there over the last 14 years, which has included 1473 patients with purulent infections of different tissues and organs, indicates the high efficacy of phage therapy.

Complete abatement of disease symptoms and return to health was noted in 1289 cases. It must be emphasized that in at least a dozen or so cases phage therapy presented the only possibility of eliminating the life-threatening infection. The therapy conducted concerned individual patients. It consisted of:

-   -   a) the growth and identification of bacterial strains isolated         from material obtained from the patient,     -   b) determination of the susceptibility of the strain to specific         phages and selection of the phage showing the highest lytic         activity towards the strain,     -   c) preparation of a phage lysate with a large number of phage         particles,     -   d) production of a sterile phage preparation for treatment.

This procedure is rather costly, laborious and time consuming. At times, 7-10 days pass from the moment of obtaining the research material to the availability of the finished, sterilized phage preparation for treatment. Such a delay is too long in certain disease states. Phage therapy on a broad scale cannot be carried out with the procedure employed thus far.

Infections accompanying mucoviscidosis present a particular problem. This is a hereditary, systemic disease consisting of dysfunction of mucous-secreting glands, predisposing the patient to chronic bronchial and pulmonary diseases. Secreted mucous is thick and sticky, making its elimination by natural routes (coughing) difficult. The accumulation and lingering of mucous in the bronchi and the impairment in clearing it create favorable conditions for bacterial infections, leading to chronic bronchitis and pneumonia. The most threatening pathogens causing infections accompanying mucoviscidosis are Staphylococcus aureus and bacilli of the genus Pseudonomas. Permanently recurring infections by these micro-organisms lead to serious pathological changes in the respiratory system and premature death. Few patients survive more than 25 years. Treatment of such infections with the available antibiotics has created a serious therapeutic problem worldwide, especially in the past few years. Antibiotic therapy of these infections has become less and less effective because the vast majority of the bacterial strains show resistance to all antibiotics, including the antibiotic of last resort—vancomycin. There is, therefore, an urgent need to introduce an alternative therapeutic method into medical practice for the treatment of refractory and highly dangerous bacterial infections.

THE GOAL OF THE INVENTION

The past years have seen a massive spread of bacterial strains resistant to all antibiotics, including vancomycin, the antibiotic of last resort. As a result, treatment of bacterial infections induced by these drug-resistant forms with antibiotics is ineffective. This situation has created dramatic therapeutic problems. Thus, there is an urgent need of introducing alternative therapeutic methods into medical practice for the treatment of refractory bacterial infections.

In consideration of the above goal, this invention is an elaboration of a method of obtaining multivalent phage strains which can be used in the production of preparations of guaranteed effectiveness in the treatment of bacterial infections without the necessity of individual phage selection in each instance. In this particular realization, the goal of the invention is the presentation of a way which allows obtaining phage preparations of high purity, in particular free of endotoxin.

A particular goal of the invention is to obtain polyvalent phage preparations which may be effectively employed in the treatment of bacterial infections connected with mucoviscidosis without the necessity of individual phage selection in each instance.

SUMMARY OF THE INVENTION

The present invention provides a method of obtaining multivalent bacteriophage strain, by which:

-   -   a) a sufficient number (n) of different strains of bacterial         pathogens of a defined genus accumulates, appearing randomly in         a given region, whereby the isolated bacterial strains are         preferably drug-resistant,     -   b) a sufficient number of different bacteriophage strains,         specific to at least one of the bacterial strains of the given         genus, accumulates,     -   c) the lytic activity of an accumulated bacteriophage strain on         each accumulated bacterial strain is determined, then the value         p, which is the proportion of the number of strains lysed by a         given phage to the number of all the accumulated bacterial         strains, is calculated.     -   d) for the resultant value of p, it is tested whether n fulfils         the condition: $n \geq {\frac{pq}{d^{2}}z_{1 - \alpha}^{2}}$         -   where: q=1−p         -   d is a constant no larger than 0.1, optimally no larger that             10% p         -   z_(1-α) is a random variable of the normal distribution             dependent on the confidence factor 1−α, which is not less             that 0.95,     -   e) the bacteriophage strain is selected which fulfils the         criterion defined in d) and has a value of p not less than 2/n,         preferably not less than 0.5.

The range of the lytic activity of each isolated bacteriophage is determined with regard to the population of pathogenic bacterial strains present in the given region. To this end, a sufficiently large collection of randomly chosen drug-resistant bacterial strains must be accumulated. With reference to the established large sample of bacteria of a population size of n strains (in the example described, n was 845 and 880, respectively, for the drug-resistant strains of Pseudomonas and Staphylococcus isolated in Poland), the frequency of success is calculated, or the proportion of the number of strains lysed by a given phage to the total number of strains studied. This frequency is regarded as the probability of success p. The probability of failure is then q=1−p.

It is essential to choose the size n that a sample must have so that it can be regarded as representative of the general population of the strains of the given genus (e.g. Pseudomonas or Staphylococcus). To this end, the following criterion for the sample to be representative is established: P(|ν−p|<d)=P(−d<ν−p<d)=1−α

The probability that the absolute value of the difference between the sample frequency ν and the probability of success p is less than the pre-assigned value of d is 1−α, which corresponds with a confidence level of 1−α. The value of 1−α is usually set at 0.95 or 0.98.

The number of samples n should fulfil the condition: $n \geq {\frac{pq}{d^{2}}z_{1 - \alpha}^{2}}$ where z_(1-α) is a random variable of the normal distribution. For 1−α=0.95, z_(1-α)=1.96, and for 1−α=0.98, z_(1-α)=2.33.

Based on this criterion and on the value of the frequency p obtained for the characterized phage, by assigning reasonable values to d and the confidence range 1−α it is possible to verify the magnitude n used to determine the range of lytic activity of a given phage and ascertain whether the lytic activity obtained for this n, with the assigned values of d and 1−α, may be regarded as correct with respect to the general population of the bacterial strains of the given genus.

The strain of bacteriophages is preferably isolated in step b) from a sample originating from the environment by passing it through a membrane filter of pore size 0.2-0.4 μm, adding culture medium to the filtrate and mixing it with a broth culture of bacteria of the defined genus, incubating this at a temperature of about 37° C. for approximately one hour, removing a portion of the suspension and smearing it onto plates with solid culture medium, incubating at approx. 37° C. for 2 to 24 hours, isolating a sample of the medium surrounding the individual bald spot, transferring it to the broth culture of bacteria of defined genus, and incubating until the culture clears, and obtaining the bacteriophage preparation by passing the lysate through a membrane filter of pore size 0.2-0.4 μm, whereby it is preferred to repeat the inoculation of the solid culture medium and re-isolation of the bald spots 5 times.

The bacterial strains in step c) are preferably inoculated onto solid culture medium, onto which a portion of the bacteriophage preparation obtained in step b) is deposited, incubated at about 37° C. for around 4 hours, after which the temperature is set at about 4° C. for around 2 to 24 hours, by which the lytic activity of the bacteriophage strain is evidenced by the appearance of, at least, individual bald spots.

It is possibly to carry out then further purification of the lysate, particularly with regard to endotoxin, whereby the mixture containing bacteriophages is in contact with a substrate containing cellulose or a partially esterified derivative of it, then rinsed with a solution that removes impurities, especially endotoxin, after which the purified bacteriophages are washed out. The endotoxin can be effectively eluted with water, a solution of a non-dissociating substance, or a saline solution of concentration no greater than 0.1 M, possibly buffered. The bacteriophage fraction can also be effectively eluted with a solution of a non-dissociating substance, or any buffer, or a saline solution of concentration greater than 0.05 M, possibly buffered. Also, elution of endotoxin and bacteriophages are carried out at temperatures between −25° C. and +100° C. Preferably, the endotoxin and bacteriophage elution can be done using an aqueous saline solution containing organic solvent. The organic solvent is best selected from a group comprising dimethyl sulphoxide, dimethylformamide, isopropanol and acetone, and as a substrate cellulose partially esterified with organic or inorganic acid can be used. It may be used a substrate of cellulose partially esterified with acetic, nitric, sulphurous or phosphoric acid, in particular cellulose may be used as a substrate of which 0.01 to 5% of the glucose molecules have been esterified, preferably 0.25 to 1%, more preferably from 0.5 to 1% of the glucose molecules.

Preferably the pathogenic bacterial strains are of the genera Staphylococcus or Pseudomonas.

A further aspect of the invention is a medication for the treatment or prevention of infections caused by bacterial pathogens which contains an active agent and a possible pharmaceutically admissible carrier, such that the active agent is comprised of a multivalent bacteriophage strain specific to the bacteria of the genus and obtained using the method of this invention.

In accordance with the invention, the medication may have the characteristic that, as a multivalent bacteriophage strain specific to bacteria of the genus Staphylococcus, it contains at least one strain of bacteriophages selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007), preferably the phages S1, S2, and S4 or S5. This medication produced in accordance with the one aspect of the invention is to serve in the treatment or prevention of infections arising in persons afflicted with mucoviscidosis and, as a multivalent bacteriophage strain specific to bacteria of the genus Staphylococcus, it contains at least one bacteriophage strain selected from among F/00002, F/00004 and F/00007.

In accordance with the invention, the medication should have the characteristic that, as a multivalent bacteriophage strain specific to bacteria of the genus Pseudomonas, it contains at least one strain of bacteriophages selected from among P1 (PCM F/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (CM F/00013), P7 (PCM F/00014), P8 (CM F/00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), optimally phages P7, P20 and P6. The medication produced in accordance with certain aspect of the invention is to serve in the treatment or prevention of infections arising in persons afflicted with mucoviscidosis and, as a multivalent bacteriophage strain specific to bacteria of the genus Pseudomonas, it contains at least one bacteriophage strain selected from among F/00010, F/00013 and F/00018.

A further object of this invention is the application of a multivalent bacteriophage strain obtained according to the method of the invention to the development of a medication for the treatment or prevention of bacterial infections caused by bacterial pathogens.

Advantageous for the production of a medication for the treatment or prevention of infections caused by bacteria of the genus Staphylococcus is the employment of at least one bacteriophage strain selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007), optimally phages S1, S2, and S4 or S5. Advantageous for the creation of a medication for the treatment or prevention of infections caused by bacteria of the genus Staphylococcus in persons suffering from mucoviscidosis is the use of at least one bacteriophage strain chosen from among F/00002, F/00004 and F/00007.

Also advantageous for the creation of a medication for the treatment or prevention of infections caused by bacteria of the genus Pseudomonas is the use of at least one bacteriophage strain selected from among P1 (PCM P/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F/00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), optimally the phages P7, P20 and P6. Advantageous for the creation of a medication for the treatment or prevention of infections caused by bacteria of the genus Pseudomonas in persons suffering from mucoviscidosis is the use of at least one bacteriophage strain chosen from among F/00010, F/00013 and F/00018. A further object of the invention is a multivalent bacteriophage strain specific to bacteria of the genus Staphylococcus selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007), optimally from among S1, S2, S4 and S5.

An object of the invention is also a multivalent bacteriophage strain specific to bacteria of the genus Pseudomonas, selected from among P1 (PCM F/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F/00015), P9 (PCM F/00016), PlO (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM P/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), optimally from among P7, P20 and P6.

Our own collection of phages active against species of bacteria which are the most frequent etiologic factors in bacterial infection in humans was used in the research. The practical examples described concern multivalent bacteriophages acting lytically on strains of staphylococci (Staphylococcus aureus), including the methicillin-resistant strains thereof, and the blue pus bacillus (Pseudomonas aeruginosa), which appear in those afflicted with mucoviscidosis in particular. These species are currently the cause of serious infections causing high mortality.

THE VIRTUES OF THE INVENTION

The introduction into therapy of polyvalent phage preparations containing multivalent phages obtained by means of this invention is a major development in combating bacterial infections which are not susceptible to treatment with antibiotics. Certain economic advantages are also connected with this new technology. It allows a significant reduction in material costs and shortens the time from collecting material for examination to obtaining the therapeutic phage preparation. Thanks to this, the phage preparation will wait for the patient, and not the patient for the production of the individual phage preparation.

The broad range of lytic phage preparations composed of several multivalent phages obtained by means of the method of this invention is a very important advantage from the viewpoint of their application in the treatment of bacterial infections. It is well known that within a bacterial population, forms resistant to a bacteriophage can appear with a frequency of about 1×10⁻⁷. In the presence of two phages, the frequency of such mutation is about 1×10⁻¹⁴, and with three phages only 1×10⁻²¹. With such an arrangement, the problem of bacterial strain resistance to phages practically does not exist.

The great applicability of the exemplified medications composed of multivalent phages deserves special emphasis. They may be employed in the medical practice in general and allow an effective means of coping with threatening bacterial infections. It is also possible to exploit phages obtained in accordance with this invention in the preparation of medications for external use, employing them, for example, in the treatment and prevention of dermatological infections. It has been found that oral administration of phage lysates obtained according to this invention increases resistance to possible future bacterial infection.

In certain cases, phage therapy can be used in conjunction with antibiotic therapy. Polyvalent phage preparations used in the treatment of bacterial infections have been show to be highly effective. Particular effectiveness has been observed in the treatment of sepsis (88% cure rate) and in the treatment of infections in patients with mucoviscidosis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents the results of the analysis of statistics acquired for phages S1-S7.

FIG. 2 presents the results of the analysis of statistics acquired for phages P1-P20.

FIG. 3 presents the results of the statistical analysis of the effectiveness of selected phage strains with regard to bacterial strains belonging to the genus Staphylococcus isolated from mucoviscidosis patients.

FIG. 4 presents the results of the statistical analysis of the effectiveness of selected phage strains with regard to bacterial strains belonging to the genus Pseudomonas isolated from mucoviscidosis patients.

For a better understanding of the essence of the invention, it is illustrated below through examples.

EXAMPLE 1 Bacteriophage Isolation

Bacteriophages for Staphylococcus and Pseudomonas were isolated from municipal sewage. The sewage was passed through a membrane filter with a pore size of 0.2-0.4 μm, which captures the bacteria but allows the bacteriophages to pass through. From the resultant filtrate, concentrated fluid culture medium was added and different dilutions of filtrate were mixed with young broth cultures of bacteria (Staphylococcus aureus or Pseudomonas aeruginosa). The samples were incubated at 37° C. for 1 hour, after which 0.2 ml of suspension was extracted from each sample with a pipette and smeared onto plates containing agar medium using a glass rod and the plates were incubated overnight at 37° C. In the event that the sought after phage was present on the plates inoculated with the suitable dilution of filtrate containing the young bacterial culture, a uniform (nebulous) growth of bacteria and separate, transparent small fields, the so-called bald spots, were observed, which usually contained several million phage particles. The individual bald spot together with the agar surrounding it were cut out with the aid of a platinum loop, then transferred to a fresh broth culture of bacteria and incubated until the culture cleared. After passing it through a membrane filter of pore size 0.2-0.4 μm, which holds back any bacteria remaining in the lysate, the filtrate contained only bacteriophages. The inoculation of different dilutions of the obtained phages with the respective bacteria on agar medium, and the re-isolation of the bald spots was carried out 5 times, which allowed obtaining a pure line of phages.

EXAMPLE 2 Determining the Susceptibility of Staphylococcus aureus Strains to Bacteriophage Microorganisms Specific to Them

Susceptibility was determined using the culture medium described by Wahl. Plates with this medium were dried at a temperature of 37° C. for 30 minutes, covered with a young, 4-hour broth culture of Staphylococcus aureus which was mixed by shaking, the excess of the suspension was removed with a pipette and again dried for 30 minutes at 37° C. On one plate, divided into 6 segments, the susceptibilities of the strain under study was determined to 6 different but specific bacteriophages. One drop of a {fraction (1/10)} bacteriophage dilution was placed onto the surface of each segment. The plates were incubated in an oven at 37° C. for about 4 hours, after which they were placed in a refrigerator until the following day. In the event of a high susceptibility of the strain to the defined phage, transparent fields are visible at the place where the phage was introduced onto the culture medium which was uniformly covered with bacterial growth, these being the result of the total destruction of bacteria cells (lysis). Less susceptibility of the strain is manifested by the appearance of individual bald spots.

EXAMPLE 3 Determining the Susceptibility of Strains of Pseudomonas to Bacteriophage Microorganisms Specific to Them

The method of determining the sensitivity was similar to that described in Example 2. In this case, though, the stock medium was agar with a phosphate buffer supplement and the incubation time of the plates deposited phage was 5 hours.

EXAMPLE 4 Selecting Phages with the Broadest Spectrum of Activity with Regard to Staphylococcus and Pseudomonas Strains—Obtaining Multivalent Phage Strains

Bacteriophages were isolated according to the method described in Example 1. The susceptibilities of 845 drug-resistant clinical strains of various species of Staphylococcus isolated from all over Poland to phages from the collection of bacteriophages specific to Staphylococcus, and the susceptibilities of 880 drug-resistant clinical strains of different species of Pseudomonas to phages from the collection of bacteriophages specific to Pseudomonas were determined.

An analysis of the susceptibilities of both groups of strains to the respective phages allowed the selection of phages of unexpectedly high activity and broad spectrum of lytic effect. These phages are presented in tables 1 and 2. TABLE 1 Phages for Staphylococcus with high lytic activity on deposit at the Polish Collection of Microorganisms (PCM), Wroclaw, Poland. POLISH COLLECTION OF PHAGE MICROORGANISMS (PCM) DESIGNATION DEPOSIT ACCESS NUMBER S1 F/00001 S2 F/00002 S3 F/00003 S4 F/00004 S5 F/00005 S6 F/00006 S7 F/00007

TABLE 2 Phages for Pseudomonas with high lytic activity on deposit at the Polish Collection of Microorganisms (PCM), Wroclaw, Poland. POLISH COLLECTION OF PHAGE MICROORGANISMS (PCM) DESIGNATION DEPOSIT ACCESS NUMBER P1  F/00008 P2  F/00009 P3  F/00010 P4  F/00011 P5  F/00012 P6  F/00013 P7  F/00014 P8  F/00015 P9  F/00016 P10 F/00017 P11 F/00018 P12 F/00019 P13 F/00020 P14 F/00021 P15 F/00022 P16 F/00023 P17 F/00024 P18 F/00025 P19 F/00026 P20 F/00027

The results for phages S1-S7 and P1-P20 were submitted to statistical analysis in order to determine whether the p values obtained for the particular phages may be considered correct for the general populations of the respective genera of bacteria. The results are presented in FIGS. 1 and 2. The calculated values of n for most of the bacteriophages were lower than the number of bacterial strains of the research samples, which suggests that the ranges of the lytic spectra are at least correct with regard to the clinical strains appearing in Poland. Considering these results, the phages listed in Tables 1 and 2 may be regarded as multivalent phages with regard to this invention.

Unexpectedly, in the case of the phages for Staphylococcus, 3 of the 7 most active, i.e. S1, S2 and S4 or S5, displayed lytic activity on 95% of the Staphylococus strains studied. Also, 3 of the 21 selected phages for Pseudomonas, i.e. P7, P20 and P6, displayed lytic activity on 87% of the Pseudomonas strains studied.

One may also regard patients suffering from mucoviscidosis as a “given region of the appearance of bacterial infection”, as defined in the essence of the invention. In the study of the pathogens appearing in this group of patients, 137 bacterial strains were used, of which 84 were identified as Pseudomonas and 53 as S. aureus. All the strains were isolated from material originating from mucoviscidosis patients from all over Poland. Analysis of the susceptibility of the strains of Pseudomonas and S. aureus studied to phages allowed the selection of phages with the highest lytic activity and the broadest range of action. Unexpectedly, in the case of phages for Pseudomonas, 3 of the 21 active phages, i.e. F/00010, F/0013 and F/00018, displayed lytic activity on 75% of the Pseudomonas strains (for the probability of success, see FIG. 3, in which phage 3=F/00010, phage 6=F/00013, and phage 11=F/00018). Among the selected phages for Staphylococcus, 3, i.e. F/00002, F/00004 and F/00007, displayed lytic activity on 98% of the Staphylococcus strains (for the probability of success, see FIG. 4, in which phage 1=F/00002, phage 3=F/00004, and phage 4=F/00007).

EXAMPLE 5 Replicating Phages to Staphylococcus and Phages to Gram-negative Bacilli, Obtaining Phage Lysates

Approximately 5% phage lysate was added to young, 4-hour cultures of Staphylococcus aureus (logarithmic phase) in broth medium supplemented by glucose. The test tubes or bottles were mixed by shaking and incubated for 3 hours at 37° C. After the appearance of a clear culture (lysis), the samples were kept cold until the following day. The lysate was passed through a membrane filter of pore size 0.2-04 , μm to remove any remaining unlysed bacteria cells. The concentration of live phage particles was determined by the two-layer method of Gratia. An incubated culture without the addition of phage lysate served as a control.

Replicating phages to Gram-negative bacilli (Pseudomonas). Peptone water was used to replicate phages to Pseudomonas. 5% phage lysate was added to a young, 4-hour culture of Pseudomonas aeurginosa, the test tubes or bottles were mixed by shaking and the samples were incubated for 5 hours at 37° C. After the culture had cleared up, the samples were left until the following day in a refrigerator, after which they were filtered through a membrane filter with pore size as above. The number of live phage particles in the lysate was determined by the method of Gratia.

The sterile broth phage lysates show long-lasting lytic activity. When kept cold, they maintain their vitality for several years, in some cases over 10 years.

EXAMPLE 6 The Production and Application of Polyvalent Phage Preparations

The sterile broth lysate obtained by the method described in Example 5, originating from the phages selected with a broad spectrum of lytic activity in Example 4, or their concentrated or further purified forms (see the following example), served in the preparation of polyvalent phage medications.

The exemplified polyvalent phage preparation to Staphylococcus is a mixture containing different amounts of the lysates of phages S1, S2 and S4 or S5, or derivatives of these lysates. For infections arising from Staphylococcus in mucoviscidosis patients, preparations from phages F/00002, F/00004 and F/00007 should be used.

The exemplified polyvalent phage preparation to Pseudomonas is a mixture containing different amounts of the lysates of phages P7, P20 and P6, or derivatives of these lysates. For infections arising from Pseudomonas in mucoviscidosis patients, preparations from phages F/00010, F/00013 and F/00018 should be used.

The medication is administered orally 3 times daily, in quantities corresponding to 10 ml of lysate, 30 minutes before meals, after previous neutralization of stomach fluids (e.g. with Gel Alumini phosphorici, purified soda or VIchy water). When applying the preparation directly onto wounds, it should be done 3 times over 24 hours. By local application, the wound should not be cleansed with disinfectant, as this may lead to inactivation of the phages. If necessary, wounds may be cleansed with a sterile culture medium or a 0.9% NaCl physiological solution.

In certain cases, phage therapy may be employed in conjunction with antibiotic therapy. The polyvalent phage preparations used in the treatment of bacterial infections have displayed high effectiveness. Particular efficacy has been observed in the treatment of sepsis (88% cure rate) and infections arising in mucoviscidosis patients.

EXAMPLE 7 Further Purification of Bacteriophage Preparations, Removing Endotoxin from Mixtures Containing Bacteriophages

In several medical applications, or also due to methods of administration (e.g. intravenously), bacteriophage preparations of high purity are required, in particular that they be devoid of bacterial endotoxin. Following the method of this invention, the affinity of bacteriophages to a substrate containing cellulose or, optimally, an esterified derivative of it, was used. A commercially available sulphated derivative of cellulose was used in this example, which was characterized by a low level of esterification (8 μmole/ml of gel). The substrate was used to remove endotoxin from the mixture containing bacteriophages. After rinsing the substrate and removing the endotoxin, the next step of purification is the elution of the adsorbed bacteriophages.

One ml of substrate containing the sulphated derivative of cellulose was put into the sterile column of a chromatograph. Efflux of the substrate from the column was prevented by sealing the lower part of the column with glass wool soaked with 70% ethanol.

The following elution buffers were prepared:

Buffer I: 0.01 M phosphate buffer, pH 7.6;

Buffer II: 0.01 M phosphate buffer, pH 7.6, containing 1 M sodium chloride.

The salts entering into the composition of the eluent were baked for 1 hour at 145° C.

The solutions were prepared using distilled apyrogenic water.

Before chromatography, 1 ml of substrate was filled into a chromatograph column rinsed with 5 ml of buffer I, and then 5 ml of buffer II.

The column was prepared for the actual chromatography by rinsing it with 10 ml buffer I.

Removal of endotoxin was accomplished by using the large-molecule fraction obtained in the molecular sieve procedure on Sepharose 4B of the concentrated bacteriophage lysate Ps PCM F/00018.

0.2 ml of the bacteriophage mixture was transferred to a chromatograph column containing 1 ml substrate containing the sulphated derivative of cellulose. A fraction of 0.2 ml volume was taken. The first fraction was eluted with 3 ml of buffer I. Under these conditions, non-associated endotoxin flowed out from the column. The second fraction was eluted with buffer II. Fraction II contained purified bacteriophages.

The results of units of endotoxin in the fractions:

The material submitted to chromatography on a substrate containing a sulphated derivative of cellulose contained 2500 units of endotoxin/ml. The fraction eluted with buffor I contained 600-1000 units of endotoxin/ml, and that eluted with buffer II contained bacteriophages devoid of endotoxin (about 1 unit/ml).

The content of endotoxin in the bacteriophage preparations was determined using the gel method of the company Charles River Endosafe, Charleston, USA. 

1. A method of obtaining multivalent bacteriophage strain charactarised in that: a) a sufficient number (n) of pathogenic bacterial strains of a specific species appearing randomly in a given region is accumulated, by which the isolated bacterial stains are possibly drug-resistant strains, b) a sufficient number of bacteriophage strains specific to at least one of the bacterial stains of the given species is accumulated, c) the lytic activity of the accumulated bacteriophage strains on each accumulated bacterial strain is determined, the value p, which is the proportion of the number of strains lysed by a given phage to the number of all the accumulated bacterial strains, is estimated, d) from the resultant value of p, it is tested whether n fulfills the condition: $n \geq {\frac{pq}{d^{2}}z_{1 - \alpha}^{2}}$ where: q=1−p d is a constant no larger than 0.1, optimally no larger that 10% p z_(1−α) is a random variable of the normal distribution dependent on the confidence factor 1−α, which is not less that 0.95 e) the bacteriophage strains is selected which fulfils the criterion in d) and has a value of p not less than 2/n, optimally not less than 0.5.
 2. The method of claim 1, wherein in step b) the bacteriophage strain is isolated from a sample originating from the environment, by passing through a membrane filter of pore size 0.2-0.4 μm, culture medium is added to the obtained filtrate and mixed with a broth culture of bacteria of a defined genus, incubated at a temperature of about 37° C. for approximately 1 hour, a portion of the suspension is removed and applied to plate with solid culture medium, incubated at approx. 37° C. for 2 to 24 hours, a sample of the medium surrounding an individual bald spot is isolated, transferred to the broth culture of bacteria of the defined genus and incubated until the culture brightens up, and the bacteriophage product is obtained by passing the lysate through a membrane filter of pore size 0.2-0.4 μm, whereby preferably the inoculation of the solid culture medium and re-isolation of the bald spots is repeated 5 times.
 3. The method of claim 1 or 2, wherein in step c) the bacterial strain under study is inoculated onto the respective solid medium, onto which a portion of the bacteriophage preparation obtained in step b) is transferred, incubated at a temperature of approximately 37° C. for approximately 4 hours, after which it is left at a temperature of approximately 4° C. for about 2 to 24 hours, after which the lytic activity of the bacteriophage strain is evident by the appearance of at least individual bald spots.
 4. The method of claim 1, wherein the pathogenic bacterial strains are of the genera Staphylococcus or Pseudomonas.
 5. The method of claim 1 or 4, wherein selected in step c) multivalent bacteriophage strain specific to drug resistant bacterial strains of the genus Staphylococcus in Poland is bacteriophage strain from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/0003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007).
 6. The method of claim 5, wherein selected in step e) multivalent bacteriophage strain specific to drug resistant bacterial strains of the genus Staphylococcus appearing in mucoviscidosis patient is bacteriophage strain from among S2 (PCM F/00002), S4 (PCM F/00004) and S7 (PCM F/00007).
 7. The method of claim 1 or 4, wherein selected in step e) multivalent bacteriophage strain specific to drug resistant bacterial strains of the genus Pseudomonas appearing in Poland is bacteriophage strain from among P1 (PCM P/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F/00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027).
 8. The method of claim 7, wherein selected in step e) multivalent bacteriophage strain specific to drug resistant bacterial strains of the genus Pseudomonas appearing in mucoviscidosis patients is bacteriophage stain among P3 (PCM F/00010), P6 (PCM F/00013) and P11 (PCM F/00018).
 9. The method of claim 1 or 2, comprising further purification of the lysate, especially from endotoxin, whereby the mixture containing bacteriophages is contacted with a substrate containing cellulose or at least partially esterified derivative thereof, which is than washed with a solution which removes impurities, especially endotoxin, after which purified bacteriophages are eluted.
 10. The method of claim 9, wherein the elution of endotoxin is carried out by means of water, a solution of a non-dissociating substance, or saline solution of a concentration not greater than 0.1 M, especially buffered.
 11. The method of claim 9, wherein the elution of bacteriophages is carried out by means of a solution of a non-dissociating substance, or any buffer, or a saline solution of a concentration great an 0.05 M, especially buffered.
 12. The method of claim 9, wherein the elution of endotoxin and bacteriophages is carried out at temperatures from −25° C. to 100° C.
 13. The method of claim 9, wherein the elution of endotoxin and bacteriophages is carried out using an aqueous solution of salt containing organic solvent.
 14. The method of claim 13, wherein the organic solvent is chosen from the group comprising dimethyl sulphoxide, dimethylformamide, isopropanol and acetone.
 15. The method of claim 9, wherein cellulose partially esterified with organic or inorganic acid is used as a substrate.
 16. The method of claim 9, wherein cellulose partially esterified with acetic, nitric, sulphurous or phosphoric acid is used.
 17. The method of claim 9 is characterized by: cellulose in which from 0.01% to 5% of glucose molecules, especially from 0.25% to 1% of glucose molecules, are esterified is used.
 18. A medicament for the treatment or prevention of infection arising from bacterial pathogen comprising the multivalent bacteriophage strain obtainable by the method according to claim 1-17 specific to bacteria belonging to genus of the bacterial pathogen.
 19. The medicament of claim 18, wherein said multivalent bacteriophage strain specific to bacteria of the genus Staphylococcus, possibly drug resistant bacterial strains of the genus Staphylococcus appearing in Poland, is bacteriophage strain selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCMF/00006) and S7 (PCMF00007), especially the phages S1, S2, and S4 or S5.
 20. The medicament of claim 18 is characterized by: it serves in the treatment or prevention of infections arising in mucoviscidosis patients and, as a multivalent bacteriophage strain specific to bacteria of the genus Staphylococcus, contains at least one bacteriophage strain from among F/00002, F/00004 and F/00007.
 21. The medicament of claim 18 wherein said multivalent bacteriophage strain specific to bacteria of the genus Pseudomonas, possibly drug resistant bacterial strains of the genus Staphylococus appearing in Poland, is bacteriophage strain selected from among P1 (PCM F/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F/00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), especially the phages P7 , P20 and P6.
 22. The medicament according to claim 18 is characterized by: it serves in the treatment or prevention of infections arising in mucoviscidosis patients and, as a multivalent bacteriophage strain specific to bacteria of the genus Pseudomonas, it contains at least one bacteriophage strain selected from among F/00010, F/00013 and F/00018.
 23. Use of multivalent bacteriophage strain obtained by the method according to claim 1-17 in the production of medication for the treatment or prevention of infections arising from pathogenic bacteria.
 24. The use of claim 23, wherein for the production of medication for the treatment or prevention of infections caused by bacteria of the genus Staphylococcus, possibly caused by drug resistant bacterial strains of the Staphylococcus appearing in Poland, at least on bacteriophage strain selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007), especially the phages S1, S2, and S4 or S5, is used.
 25. The use of claim 23, wherein for the production of medication for the treatment or prevention of infections arising in mucoviscidosis patient caused by bacteria of the genus Staphylococcus, at least one bacteriophage strain from among F/00002, F/00004 and F/00007 is used.
 26. The use of claim 23, wherein for the production of medication for the treatment or prevention of infections arising from bacteria of the genus Pseudomonas, possibly caused by drug resistant bacterial strains of the genus Pseudomonas appearing in Poland, at least on bacteriophage strain from among P1 (PCM F/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F/00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020) P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), especially the phages P7, P20 and P6, is used.
 27. The use of claim 23, wherein for the production of medication for the treatment or prevention of infections arising in mucoviscidosis patients caused by bacteria of the genus Pseudomonas, at least on bacteriophage strain selected from among F/00010, F/00013 and F/00018 is used.
 28. The multivalent bacteriophage strain selected from among S1 (PCM F/00001), S2 (PCM F/00002), S3 (PCM F/00003), S4 (PCM F/00004), S5 (PCM F/00006), S6 (PCM F/00006) and S7 (PCM F/00007), wherein the strain characterised as specific to bacteria of the genus Staphylococcus possibly specific to drug resistant bacterial strains of the genus Staphylococcus, appearing in Poland.
 29. The multivalent bacteriophage strain selected from among P1 (PCM F/00008), P2 (PCM F/00009), P3 (PCM F/00010), P4 (PCM F/00011), P5 (PCM F/00012), P6 (PCM F/00013), P7 (PCM F/00014), P8 (PCM F00015), P9 (PCM F/00016), P10 (PCM F/00017), P11 (PCM F/00018), P12 (PCM F/00019), P13 (PCM F/00020), P14 (PCM F/00021), P15 (PCM F/00022), P16 (PCM F/00023), P17 (PCM F/00024), P18 (PCM F/00025), P19 (PCM F/00026), and P20 (PCM F/00027), wherein the strain is characterised as specific to bacteria of the genus Pseudomonas, possibly specific to drug resistant bacterial strains of the genus Pseudomonas appearing in Poland. 